Dracaena are vulnerable to a potentially severe leaf and stem disease caused by the Fusarium moniliforme fungus. The fungus causes dark brown and yellow patches on its host's foliage and decays stem tissue supporting the plant's leaves. A bacterial rot disease caused by a variation of the Erwinia carotovora bacteria produces similar symptoms to a Fusarium infection. A number of generic fungal leaf spot diseases cause brown and yellow spots on dracaena leaves. The pathogens responsible for this general condition rarely cause serious harm, but they may deal some cosmetic damage to the plant and diminish its growth.
Insect pests can discolor the tips of leaves and stems as they feed on the plant's tissues. Scales, largely stationery insects with rigid exteriors, are sap-sucking pests that can infest dracaena. Scales latch onto the surface of stems, branches and leaves and feed on the sap of their host. They disrupt the circulatory system of the plant by preventing the sap from flowing to the outer regions of the plant. This causes leaves, flowers and shoots attached to infested growth to wither and die. Leaf damage often begins at the tip and edges of damaged foliage. Mealybugs and fungus gnats also feed on dracaena at certain stages during the developmental cycle. These insects can spread bacterial and viral pathogens and may help fungi establish themselves on a healthy plant.
A dracaena planted in soil containing toxic compounds may exhibit symptoms of stress from the chemical damage. Dracaena is one of several plant species that are particularly susceptible to fluoride toxicity. Excess fluoride in the soil causes brown spots on the edges of the plant's bladed foliage. The decaying spots are less than an inch wide and often link together. Exposure to salts from road treatments and fertilizers may also cause discolorations along the tips of dracaena leaves.
A deficiency of a critical mineral or nutrient may be to blame for the browning of stems and leaves on dracaena. Dracaena prefers a soil pH level between 6.0 and 6.5. Soil with a higher or lower pH may prevent the plant form absorbing nutrients from the soil. A deficiency of magnesium or calcium can cause the leaf margins of dracaena to decay, causing unsightly discoloration and loss of leaves.